Methotrexate (MTX) has been used as the primary treatment for ectopic pregnancies; however; it raises the risk of a life-threatening adverse drug reaction such as pancytopenia [1]. We present a case of MTX-induced pancytopenia in a patient with ectopic pregnancy, which may be idiosyncratic and perhaps unavoidable, and we identify a few early signs of MTX toxicity that might assist in monitoring in order to minimize unintended consequences in patients.
A 27-year-old woman (gravida 2 and para 1), whose body surface area was 1.46 kg/m2, presented without contributory medical history. She was diagnosed with ectopic pregnancy based on the findings of an ultrasound scan (ectopic mass: 1.9 cm) and hCG titer (1774.8 mIU/ml). In pre-treatment evaluations, hemoglobin (Hb: 13.1 g/dl), white blood cells (WBC: 7.72 × 109/l), platelet count (262 × 109/l), blood urea nitrogen (8 mg/dl), serum creatinine (0.51 mg/dl), aspartate aminotransferase (11 U/l), and alanine aminotransferase (11 U/l) were in the normal range. She was subsequently administered a single dose of 50 mg MTX intramuscularly; however, on day 4 after MTX initiation she presented with severe vomiting and mucositis, which limited her daily dietary intake. On day 6, she went to the emergency service due to fever (39.3°C). Although her vital signs were stable (blood pressure: 103/66 mm Hg, pulse rate: 91 beats/min, respiratory rate: 20 breaths/min), hematological assessment revealed febrile neutropenia (WBC: 0.7 × 109/l, neutrophils: 27.0%, Hb: 11.5 g/dl; platelet count: 174 × 109/l). She received a granulocyte colony-stimulating factor agent (filgrastim 300 µg/day) and an empiric broad-spectrum antibiotic for febrile neutropenia. Because her prior complete blood counts were normal, we suspected MTX as the likely cause of neutropenia. She started leucovorin 120 mg/day as a rescue therapy on day 7, but anemia (nadir of Hb was 8 g/dl on day 10; hematocrit: 23.5%; mean cell volume: 92.2 fl) and thrombocytopenia (nadir of platelet count was 11 × 109/l on day 12) were found on the following days. Although bone marrow evaluations were indicated to rule out malignancy and myelodysplasia, the patient did not accept a biopsy. She was transfused with blood products including packed red blood cells and platelets. Her hematologic parameters returned to the normal range and her condition improved gradually after 3 weeks from admission.
Pancytopenia has been reported in 3% of patients with rheumatoid...